Its more for flavor than anything. We had a Dragonborn Fighter with a serious fear/respect thing going on for stronger creatures. We ruled that he was almost always tipping an ethereal fedora as a nervous reflex given how he acted and the way he spoke.

If i had to guess though it would be a legendary with a +2 to attack rolls when thrown and it would appear back in your hands after being thrown with a 30 or higher on percentile die. When moving and dribbling, it would probably add proficiency with dex. saves or advantage if already proficient and a +2 bonus to sleight of hand checks. You would have disadvantage on Strength checks because of one hand on the basketball and disadvantage on stealth because of the sound the ball makes while dribbling.

Every decision in every game should have the option to punch their fucking balls.

"PROTAGONIST! If you think you have defeated me, you are mistaken! Now choose... Save the world, or save your love!"

A: Save world
B: Save love
C: Punch them in the fucking balls.